- #1

dijkarte

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A function ψ:A --> B is the set:

ψ = { (x, y) | [itex]\forall[/itex]x[itex]\in[/itex]A[itex]\exists[/itex]y[itex]\in[/itex]B[itex]\ni[/itex](((x, y) [itex]\in[/itex] ψ) [itex]\wedge ((x, z)\in[/itex] ψ) [itex]\Rightarrow[/itex] y = z)}

Thanks.